In Young's double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is immersed in a liquid of refractive index $$\frac{4}{3}$$ without changing geometrical arrangement, the new fringe width will be

An unpolarised beam of intensity I$$_0$$ is incident on a pair of nicols making an angle of 60$$^\circ$$ with each other. The intensity of light emerging from the pair is

In Young's double slit experiment with sodium vapour lamp of wavelength 589 nm and slit 0.589 mm apart, the half angular width of the central maxima is

Two identical light waves, propagating in the same direction, have a phase difference $$\delta$$. After they superpose the intensity of the resulting wave will be proportional to